Effect of the porous structure of the support on hydrocarbon distribution in the FischereTropsch reaction

Abstract

Emissions standards are increasingly stringent due mainly to its impact on the environment. Although the diesel engine is an attractive solution for carbon dioxide reduction, a challenge remains to simultaneously control nitrogen oxides and matter particulate emissions to accepted levels. On engine tests, it has been observed that FischereTropsch diesel significantly reduces CO, HC, PAHs and particulate emissions compared to oil derived diesel. However, selectivity control in Fischer Tropsch Synthesis is still a key challenge due the Anderson-Schultz-Flory polymerization mechanism followed by hydrocarbon distribution. In this work we are presenting the first steps towards a new strategy that can tune, in one step, the selectivity to desired products by taking advantage of the shape selectivity properties of SBA-15 mesoporous silica used as support. Co-SBA-15 (30%wt) catalysts with different pore size were prepared by excess solution impregnation. Our results show that pore diameter not only affects the size and reducibility of Co particles but it also significantly influence the liquid products distribution, with the high molecular weight hydrocarbon fraction increasing on large pores, attributed to the existence of a shape selectivity effect induced by the textural properties of the catalyst namely its pore size and pore volume.